- Unplug all external peripherals including secondary monitors
- At this point the SoftwareUpdaterLauncher should allow the Apple Menu to work.
- Select the Apple Menu Logout button.
- Count to five.
- Click your heels together and repeat: "I want to go back to
- Take a deep breath and press the Return/Enter key.
- After a second or so you will see life again: a prompt on whether to Restart or to install and Restart. Since you're here for that update, you might as well choose Install and reboot.
- Watch it install, and restart.
- There is no next step. You are done. If not, try the Apple support forums.